The long-awaited BlackBerry App World opened its doors Wednesday, kicking off the Cellular Telecommunications Industry Association show 2009 (CTIA 2009) in Las Vegas. BlackBerry App World is Research in Motion’s (RIM) effort to keep BlackBerry a worthy contender in the battle for the top smartphone.

BlackBerry App World lets you browse, purchase and download apps directly to your BlackBerry. To download the storefront, visit mobile.blackberry.com or www.blackberry.com/appworld from the BlackBerry Browser. A BlackBerry App World icon will appear on your homescreen when it is done downloading. Before you can begin purchasing, however, you must set up a PayPal account on your PC.

The App World homescreen displays a number of featured apps daily. A toolbar runs across the bottom of the screen with four shortcut icons: Categories, Top Downloads, Search and MyWorld. Categories lists apps by genre such as Games, Music and Video, News and Weather, etc. You can refine the list even further by typing a few letters of what you’re looking for into the input box at the top of the screen. If you know what app you’re looking for, you can click the Search and find it by name. Clicking the My World icon, lets you write reviews, recommend and uninstall/re-install downloaded applications.

After you click on an app, you’ll see a Details screen with additional information about the app as well as its price and rating. You can also jump to user reviews and screenshots of the app. To begin downloading, you either click “Purchase” or “Download” (for free apps). Once downloaded, the apps can be found in the Downloads folder on the homescreen of your phone.

BlackBerry App World will work with RIM devices running BlackBerry OS (version 4.2 or higher) that have a trackball or a SurePress touchscreen (as in the BlackBerry Storm).